BEIRUT, LEBANON
— A heated diplomatic campaign waged by the United States and Israel against Iran and its Lebanese protégé, Hizbullah, could have an unintended and potentially destabilizing backlash.

Instead of cowing Tehran and its Islamist allies, the verbal salvoes and Israel's hardline policies against the Palestinians are providing encouragement and inspiration to Hizbullah and radical Palestinian groups such as Hamas and Islamic Jihad. The result could be a new explosion of violence in the Middle East.

"Hizbullah and Iran feel comfortable that the drums of war are beating so loudly," says Professor Nizar Hamzeh, head of the political science department of the American University of Beirut.

Israel's accusations have received sympathy in Washington. Last week, President Bush described Iran as part of an "axis of evil" along with Iraq and North Korea. Ironically, Hizbullah and Iranian conservatives take quiet satisfaction from the increasing polarization between Washington and Tehran.

"Hizbullah's long-term interests of liberating Jerusalem and forging an Islamic anti-Israel resistance have been given a boost because of the collapse of the peace process and the post-September 11 events," Professor Hamzeh says.

The indication emerging from south Lebanon is that Hizbullah is preparing for war. Hundreds of battle-hardened fighters, veterans of Israel's 22-year occupation of southern Lebanon, are marshaled along the border with Israel. A massive arsenal, including rockets and missiles, has been stashed away in the border district, confirm well-placed sources in southern Lebanon.

Some members of Hizbullah say it is only a matter of time before Israel is attacked from Lebanon. "This will happen, and we are constantly preparing for it," says a Hizbullah insider with military connections. "Israel will be attacked at the right time, and when we do, the whole of the Middle East will change."

Strong words for an organization that has been cited as second only to Osama bin Laden's Al-Qaeda network on Washington's list of terrorist targets.

Although Hizbullah's leadership has not been so explicit, the group's south Lebanon commander, Sheikh Nabil Qaouk, has said that Hizbullah's "missiles on the border" would deter Mr. Sharon's "terrorist actions" against Lebanon. The defiance of Hizbullah and its patron Iran, in the face of the combined weight of the US and Israel, can be explained by the group's fundamental opposition to the Jewish state.

Hizbullah was born to fight. It emerged in the wake of Israel's 1982 invasion of Lebanon and over the next few years was honed into a formidable guerrilla force. Using classic hit-and-run tactics, Hizbullah's fighters forced the Israeli army to withdraw from southern Lebanon in May 2000.

But in the wake of Israel's withdrawal, a question mark hung over Hizbullah's future.

What does a party based on jihad do when there is nothing left to resist or struggle against? The outbreak of the Palestinian intifada, or uprising, in September 2000, granted Hizbullah a new relevance. Israel's declining economy as well as the recent refusal of some reservists in the Israeli army to serve in the Palestinian territories encourage Hizbullah to believe that the Jewish state's morale is slipping and is heading for disintegration. Hizbullah's officials have referred to this being "the era of the collapse of Israel."

Furthermore, according to Hamzeh, President Bush's "war on terror" and the US administration's open hostility to Hizbullah simply strengthens the group's role as exemplar to other Islamist organizations in the Middle East.

Even Israel's overwhelming military superiority fails to worry Hizbullah. "We have something they don't," says the Hizbullah insider. "We seek martyrdom, they love life. We can endure suffering, they cannot."

Go for a drive along the Lebanon-Israel border and there are no obvious signs of the 10,000 rockets. But a well-connected source says they are there, maybe not as many as 10,000, yet enough to create havoc in northern Israel if the opportunity arises.

The source refers to "truck after truckload" of weapons brought to the border district between May 2000 and last December. But for now they remain hidden out of sight. The Hizbullah fighters are easier to spot. They man small observation posts along the border fence, often directly opposite heavily fortified Israeli army outposts.

In two places close to the border, Hizbullah fighters man 57mm antiaircraft guns. Lebanese airspace is breached almost daily by Israeli warplanes, which the United Nations condemns as "provocative."

In the past two weeks, Hizbullah has begun firing at the warplanes. The large-caliber rounds cross the border and explode with a loud bang thousands of feet in the air above Israeli towns, spattering the ground with light shrapnel.

Hizbullah's shooting is designed to cause panic rather than injuries. But UN and US diplomats in Beirut have publicly expressed concern that Israel's overflights and the antiaircraft shooting could trigger a cross-border escalation.

"In the light of the situation elsewhere in the region, it is a very tense moment," says US diplomat Carol Kalin in Beirut.